The invention relates to a device for monitoring neutral and earth conductors comprising:                processing means to supply a loss of neutral detection signal, and        first voltage detection means designed to be connected between a neutral conductor and an earth conductor to supply a first signal representative of a voltage between neutral and earth to said processing means.        
The invention also relates to an electrical switchgear apparatus comprising main electrical contacts connected between an input and an output, a trip relay for triggering opening of said main contacts, the input comprising a neutral conductor terminal, an earth conductor terminal and at least one phase conductor terminal.